Self-aligning slitting apparatus for traveling webs

ABSTRACT

An apparatus for slitting a longitudinally traveling elongate web having both longitudinally extending thickened and thinned portions joining each other at one longitudinal side edge of the thickened portion and being characterized by its ability to selfalign to compensate for deviations in the path of travel of the one longitudinal side edge. A sensing means and severing means are mounted for transverse movement with each other with the sensing means being disposed for alternative engagement with the thickened and thinned portions and with the severing means being disposed for longitudinally slitting the traveling web along a predetermined path. A reciprocating means is provided for continuously shifting the sensing means and severing means in alternative opposite transverse directions and is controlled by control means responsive to the sensing means for actuating the reciprocating means to transversely shift the sensing means and severing means to continually compensate for deviations in the path of travel of the one longitudinal side edge of the thickened portion.

[451 May 23, 1972 7] ABSTRACT An apparatus for slitting a longitudinally traveling elongate y extending thickened and ther at one longitudinal side g characterized by its eviations in the path of A sensing means and w ldA p .n nl .n n mvmhwm mmm mwfiwmw fi m mm mm mh v Wm Wn m c o l.ml mo Um m e S C t n m m .s e m mmmmwn mm m m d hd m af v mwmmnwmmx nc ma twm w m m g r emm cmfl e m mmmmm m mm m mu b md smm 4 mm m w. 3 mm? E n vmm ius m C fl m 5.. m mww m mmwmmwemwu a w mnvnam em n 5 mm m m o e woe mm m mwm R m m me W emn mm mmwmmm u mwmmmmmumm mwm 6 I Primary Examiner-Frank T. Yost APPARATUS FOR TRAVELING WEBS ym", Bell, r, rk & son 721 lnventori Charles E. Brocklehurst, Augusta, Ga. [5

Rlegel Textile Corporation, Ware Shoals, web having both longitudinal] Apt 8, 1970 thinned portions joining each 0 edge of the thickened portion and bein [21 Appl- N .2 2 ability to self-align to compensate for d travel of the one longitudinal side edge.

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[22] Filed:

Q PATENTEDMAY 23 1972 SHEEI 1 OF 3 FROM SUPPLY Somme INVENTOR.

T TAKECBU P CHARLES E. BROCKLEHUEST ATTORNEY-S FATENTEDHAYZB I972 SHEET 2 UF 3 CHARLE$ E. BEocKLEHuRsT ATTORNEYS PATENTEDMAYZS I972 SHEET 3 0F 3 INVEN TOR I ATTENUATOR I l CHARLES E. BQOCKLEHUBST AMPu FIEQ FEEDBACK Q; AMPUFIEB l J [OI 51 Rammae OUQCE- gESSUEE':

I m .ND\CATOR ATTORNEYS This invention relates to an apparatus for slitting a longitudinally traveling elongate web having both longitudinally extending thickened and thinned portions joining each other at a longitudinal side edge of the thickened portion.

In the manufacture of various products, an elongate web having both longitudinally extending thickened and thinned portions is often formed as an intermediate product on which it is necessary to conduct some further operation, such as slitting the web longitudinally thereof in predetermined relation to the longitudinal side edge of the thickened portion adjoining the thinned portion.

For instance, in the weaving of fabric for the formation of diapers and the like, it is conventional practice to weave a fabric having a width several times the width of the diapers, etc. to be formed, so that multiple strips of diaper or the like material may be formed simultaneously on a given loom to maintain high rates of production with minimum equipment. The strips are typically joined by a thinned portion which results from the omission of warp yarns, employing a thinner weave or the like. The fabric is then slit by conventional severing means longitudinally of the thinned portions and preferably in predetermined relation to the one longitudinal side edge of the thickened portion.

Heretofore, it has been conventional to slit the fabric while advancing it along a predetermined longitudinal path of travel with conventional severing means positioned stationary adjacent the path of the one longitudinal side edge for slitting the fabric therealong. However, this method has not proven to be entirely satisfactory due to problems encountered in advancing the one longitudinal side edge of the thickened portion along a substantially constant line of travel in predetermined relation to the severing means. In addition, variations in width ofthe thickened portion contribute to the deviation of the one longitudinal side edge of the thickened portion from travel along a substantially constant line in predetermined relation to the severing means. It will be readily apparent that deviations in the path of travel of the one longitudinal side edge will prevent slitting of the fabric in predetermined relation to the one longitudinal side edge.

Thus, it is an object of this invention to provide an apparatus for slitting a longitudinally traveling elongate web having both longitudinally extending thickened and thinned portions joining each other at a longitudinal side edge the thickened portion and characterized by its ability to self-align to compensate for deviations in thepath of travel of the one longitudinal side edge.

It is another and more specific object of this invention to provide such an apparatus for slitting such a web including sensing means for continuously sensing the path of travel of the one longitudinal side edge and severing means operatively associated with the sensing means, which means are continually shifted transversely of the traveling web in response to the sensing means to self-align and compensate for any deviations in the path of travel of the one longitudinal side edge.

By this invention, the above objects are accomplished by providing an apparatus including sensing means mounted for transverse shifting movement with respect to the traveling web and disposed on one side of the traveling web for alternative engagement with the thickened and thinned portions thereof, and severing means mounted for movement with the sensing means and for longitudinally slitting the traveling web along a predetermined path. A double-acting reciprocating means is operatively connected with the sensing means and severing means for continuously shifting the same in alternative opposite transverse directions and is actuated by control means responsive to the sensing means for actuating the reciprocating means in accordance with the engagement ofthe sensing means with one of the thickened and thinned portions of the traveling web to transversely shift the sensing means and severing means in a direction toward the other of the thickened and thinned portions.

The apparatus preferably includes support means disposed on the other side of the traveling web in opposed relation to the sensing means for supporting the portion of the traveling web in engagement with the sensing means. The sensing means preferably comprises a sensing head disposed for movement under the influence of the traveling web substantially perpendicular to the traveling web for alternative engagement with the thickened and thinned portions.

The control means preferably comprises a pair of substantiallyidentical current carrying coils mounted outwardly of the sensing headand longitudinally aligned in end-to-end relation, an elongate armature or magnetic core mounted longitudinally within the pair of current carrying coils and being operatively connectedto the sensing head for movement longitudinally of' the pair of current carrying coils in response to movement of the sensing-head perpendicular to the traveling web for changing the respective impedance of each of the coils and circuit means operatively associated with the reciprocating means and responsive to changes in the impedance of the coils for actuating the reciprocating means. Thecircuit means may include switch means having a first and second position with the switch means being in one of the positions when the sensing head is in engagement with the thickened portion for actuating the reciprocating means to transversely shift the sensing head and severing means toward the thinned portion and is' in the other position when the sensing head is in engagement with the thinned portion for actuating the reciprocating means to transversely shift the sensing head and severing means toward the thickened portion.

Some of the objects of the invention having been stated, other objects will appear as the description proceeds, when taken in connection with the accompanying drawings, in which:

FIG. 1 is a schematic perspective view with portions broken away illustrating an apparatus incorporating the features of the present invention;

FIG. 2 is an enlarged sectional view taken substantially along the line 22 of HO. 1;

FIG. 3 is a sectional view taken substantially along the line 3-3 ofFlG. 2; and

FIG. 4 is a diagrammatic view illustrating control means for the apparatus of FIG. 1.

With reference specifically to FIG. 1, there is illustrated a longitudinally traveling elongate web 10 having three longitudinally extending thickened portions 12 joined or otherwise interconnected by thinned portions 14 at longitudinal side edges 12a of the thickened portions 12. As schematically indicated, the web 10 is advanced from a suitable supply source to a conventional take-up means along a predetermined longitudinal path of travel through an apparatus, generally designated at 20, incorporating the features of the present invention for slitting the traveling web 10 longitudinally along the thinned portions 14 in predetermined relation to a longitudinal side edge 12a of the thickened portions 12.

While the apparatus 20 will be hereinafter described for slitting the above-described web 10, it will be apparent that any other web having longitudinally extending thickened and thinned portions may beslit with an apparatus constructed in accordance with the present invention without departure from the spirit of this invention.

The apparatus 20 includes a pair of spaced apart, vertical, channel-like, support members 21 which may be supported from a suitable horizontal supporting structure such as the floor of a building, not shown. Support members 21 are connected by spaced apart horizontal guide bars 22 which guide the traveling web 10 between support members 21 along a predetermined longitudinal path of travel from the supply source to the take-up means. Support members 21 are, additionally, joined by a shaft 23 disposed parallel with guide bars 22 and to one side of the path of travel of the traveling web 10 and on which is mounted separate self-aligning slitting apparatus, generally designated at 30 and 30, respectively, for

slitting the traveling web along thinned portions 14 in accordance with the present invention. Inasmuch as both of the apparatus 30 and 30 are identical or mirror images of each other, except that they are arranged for slitting the traveling web 10 along different thinned portions 14, only apparatus 30 will be hereinafter described in detail, the other being represented in the drawings by like reference characters with the addition of a prime notation.

As previously indicated, self-aligning slitting apparatus 30 is mounted on shaft 23 and comprises an elongate support plate 31 disposed adjacent one side of the traveling web 10 and carried by a pair of spaced apart blocks 32 and 33 which are slidably mounted on shaft 23 to mount support plate 31 for transverse shifting movement relative to the traveling web 10. In order to prevent blocks 32 and 33 and support plate 31 from pivoting about shaft 23, block 32 is additionally slidably mounted on a shaft 34 carried by support member 21 and disposed parallel to and in spaced relation from shaft 23.

As best illustrated in FIGS. 1 and 2, a brace 36 having a vertical portion 36a disposed parallel to traveling web 10 is connected to support plate 31 by a bolt 37 disposed through an elongate slot 31a in plate 31 which extends transversely of the traveling web 10 to facilitate adjustment of brace 36 on plate 31 transversely of traveling web 10. A generally planar support member 38 is mounted on vertical portion 36a of brace 36 in supporting relation to one side of the traveling web 10 as it advances along its predetermined path of travel.

An inverted L-shaped carriage 39 having vertical and horizontal leg members 39a and 39b, respectively, is disposed on the other side of the path of travel of the traveling web 10 with vertical leg member 39a being disposed in opposed relation to support member 38 and connected to brace 36 by a narrow torpedo-shaped connecting member 41 which extends across the path of the traveling web 10, as best illustrated in FIGS. 2 and 3. Thus, carriage 39 and support member 38 are connected for movement together. As is apparent from the foregoing description, carriage 39 and support member 38 may be adjusted transversely ofthe traveling web 10 by proper adjustment of brace 36 on support plate 31 for positioning relative to the path of one of the thinned portions 14 and may be shifted transversely of traveling web 10 by transversely shifting plate 31 relative to shaft 23.

A sensing means comprising an elongate sensing head 42 is pivotally mounted as at 43 and 44 by connecting link 45 to horizontal leg member 39b of carriage 39. The elongate sensing head 42 is disposed through a generally rectangular slot 46, FIG. 3, in vertical leg member 39a of carriage 39 for alternative engagement with an elongate portion of the thickened and thinned portions 12 and 14, respectively, adjacent one longitudinal side edge 12a of the thickened portion 14. Through pivot connections 43 and 44, the sensing head 42 is mounted for movement perpendicular to the traveling web 10 and is normally biased by means to be hereinafter described into engagement with the traveling web 10. Thus, the sensing head 42 is movable under the influence of the traveling web 10 out of engagement with one of the thickened and thinned portions 12 and 14, respectively, into engagement with the other. This movement may be brought about from either a deviation in the path of travel of the one longitudinal side edge 12a or transverse shifting of sensing head 42. It will be apparent that support member 38 will support the portion of traveling web 10 engaged by sensing head 42. Since sensing head 42 engages an elongate portion of either of the thickened and thinned portions 12 and 14, respectively, slight variations in thickness of the portion which the sensing head 42 is in engagement with will not cause the sensing head 42 to be moved perpendicular to the traveling web 10.

A severing means 50 including a rotary cutting blade 51 is suitably mounted by bracket 52 to vertical leg member 39a of carriage 39 in predetermined relation to sensing head 42 with a portion of the cutting blade 51 extending through a slot 53 of vertical leg member 39a of carriage 39 for longitudinally slitting the traveling web 10. The rotary cutting blade 51 may be driven by any suitable means such as a motor 54 having a drive gear 55 that meshes with a gear 56 that is drivingly connected to rotary cutting blade 51, FIG. 3. As illustrated in FIG. 3, the torpedo-shaped connecting member 41 that connects brace 36 and carriage 39 is mounted in alignment with rotary cutting blade 51 after the traveling web 10 is slit so that the connecting member 41 extends through the traveling web 10 at the location of the slit formed by cutting blade 51 and does not otherwise interfere with the predetermined path of travel of the traveling web 10. Preferably, the cutting blade 51 is offset to the left as viewed in FIGS. 1 and 3 relative to sensing head 42 transversely of traveling web 10 about one-half the width of thinned portion 14 for longitudinally slitting the web 10 within the thinned portion 14 adjacent the one longitudinal side edge 12a.

A- double-acting reciprocating means is operatively connected to support plate 31 for transversely shifting support member 38 and carriage 39 relative to the traveling web 10 and comprises a double-acting, fluid-operated piston and cylinder assembly 60 including a cylinder 61 mounted on support member 21 as at 62 with the free end of piston 63 drivingly connected as at 64 to support plate 31 so that the forward and reverse strokes of piston 63 transversely shift support plate 31 in alternative, opposite, transverse directions relative to the traveling web 10. A solenoid actuated fluid valve 65 is provided for controlling the supply of fluid under pressure from pressure source 66, FIG. 4, to the double-acting, fluid-operated piston and cylinder assembly 60 and thus, the direction of transverse shifting of support plate 31. The operation of fluid valve 65 will hereinafter be more fully described.

The control means for self-aligning slitting apparatus 30 is diagrammatically illustrated in FIG. 4 and is responsive to the position of the sensing head 42 for actuating the reciprocating means in accordance with engagement of the sensing head 42 with one of the thickened and thinned portions 12 and 14, respectively, of the traveling web 10 to transversely shift support plate 31 and the support member 38, carriage 39, sensing head 42 and cutting blade 51 carried thereby in a direction toward the other of the thickened and thinned portions 12 and 14, respectively. More particularly, the control means comprises a pair of substantially identical current carrying coils 71 and 72 which, as illustrated, are longitudinally aligned in endto-end relation outwardly of sensing head 42 and are preferably carried in a housing 73 that is mounted to horizontal leg member 39b of carriage 39 as by bracket 74, FIG. 2. An elongate armature or iron core 75 is mounted longitudinally within coils 71 and 72 for movement longitudinally thereof. Armature 75 is biased by spring 76 toward the sensing head 42 into contact with a stud, bolt or the like 77 carried by sensing head 42 for movement longitudinally of the coils 71 and 72 in response to movement of the sensing head 42 perpendicular to the traveling web 10. With the coils 71 and 72 being substantially identical, the impedance of each of the coils will be substantially the same when armature 75 is disposed equally between the two coils 71 and 72. However, upon displacement of the armature 75 longitudinally of the coils 71 and 72, the respective impedance of coils 71 and 72 is changed. Thus, with armature 75 positioned equally between coils 71 and 72, as illustrated, when the sensing head 42 is in engagement with the thickened portion 12 adjacent the one longitudinal side edge 120, the respective impedance of coils 71 and 72 will be changed when sensing head 42 moves out of engagement with the thickened portion 12 into engagement with the adjoining thinned portion 14 under the influence of the traveling web 10 due to deviation of the longitudinal side edge 12a of the thickened portion 12 and/or transverse movement of sensing head 42.

In accordance with the present invention, the control means includes circuit means responsive to changes in the impedance of coils 71 and 72 and which is operatively associated with the reciprocating means for controlling the actuation thereof. The circuit means includes, FIG. 4, an oscillator 81 having a symmetrical transformer, not'shown, forming a bridge with coils 71 and 72 for detecting any differential in impedance of coils 71 and 72. When the impedance of coils 71 and 72 are different, that is, when the sensing head 42 is in engagement with the thinned portion 14, a corresponding signal is transmitted to an amplifier 82, rectified by rectifier 83, visually indicated on indicator 84 and transmitted to a meter relay 90 to be hereinafter described. An attenuator 85 may be included in the circuit means for controlling the sensitivity of the circuit means. In addition, a feedback unit 86 is preferably included for feeding a signal back to the input of the amplifier 82 for adjusting the circuit means to insure that a plus or positive signal is generated when the sensing head 42 is in engagement with the thickened portion 12. Furthermore, through adjustment of the feedback unit 86, the apparatus 30 of the present invention can be readily adjusted for use with a traveling web of different thickness without mechanical adjustment of the sensing head 42.

The meter relay, generally designated at 90, includes a stationary permanent magnet moving coil meter 91 which comprises a U-shaped permanent magnet 92 having a north (N) and south (8) pole and a movable coil 93 which is disposed around a fixed iron core 94. When sensing head 42 is in engagement with thickened portion 12, a positive signal is received by coil 93 in proportion to the signal produced from the difference in impedance of coils 71 and 72 and the resulting magnetic field reacts with the magnetic field of magnet 92 to exert a rotating force on coil 93 and vane 95 carried thereby. A coil spring 96 is operatively associated with vane 95 to provide a restoring force to coil 93 for balancing the rotating force on coil 93 and vane 95 after a predetermined rotation thereof. Vane 95 is disposed adjacent a light beam emitted from a light source 97 and received by a photoelectric cell 98 and is positioned for interrupting the beam when a positive signal is received by coil 93 or in other words when sensing head 42 is in engagement with thickened portion 12. When sensing head 42 is in engagement with thinned portion 14, a minus or negative signal is received by coil 93 to rotate vane 95 out of the path of the light beam.

An amplifier 100 is operatively connected to light source 97 and photoelectric cell 98 and is responsive to interruptions in the light beam for controlling the energization of relay coil 101 which in turn controls the position of a single pole, double-throw relay switch 102. Relay switch 102 has a first and second position and is spring biased as indicated in a first position when the light beam is interrupted by vane 95 and is shifted to the second position by relay coil 101 when the light beam is uninterrupted. When relay switch 102 is in the first spring biased position, a solenoid 103 of fluid valve 65 is energized to position core 104 of valve 65 for supplying fluid under pressure from pressure source 66 to the forward side of piston head 105 of piston 63 to transversely shift sensing head 42 and cutting blade 51 toward the thinned portion 14 or to the left as viewed in the various Figures. When relay switch 102 is in the second position, solenoid 106 of valve 65 is energized to position core 104 for supplying fluid under pressure from pressure source 66 to the back side of piston head 105 of piston 63 to transversely shift sensing head 42 and cutting blade 51 toward the thickened portion 12 or to the right as viewed in the various Figures.

In operation, the self-aligning slitting apparatus described above is positioned for operation at one longitudinal side edge 12a of the thickened portion 12 such that the cutting blade 51 is set for slitting the web 10 along the adjoining thinned portion 14. As the elongate web 10 is advanced along its predetermined path of travel, the sensing head 42 and cutting blade 51 are continually shifted in alternative, opposite, transverse directions relative to the longitudinal side edge 12a of the thickened portion 12. More particularly, when the sensing head 42 is in engagement with the thickened portion 12 adjacent the one longitudinal side edge 12a, the reciprocating means is actuated to transversely shift the sensing head 42 and cutting blade 51 across the one longitudinal side edge 12a toward the adjacent thinned portion 14. As soon as the sensing head 42 moves out of engagement with the thickened portion 12 into engagement with the adjoining thinned portion 14, the reciprocating means transversely shifts the sensing head 42 and cutting blade 51 across the one longitudinal side edge 12a toward the thickened portion 12. Thus, the sensing head 42 and cutting blade 51 are being continually shifted relative to the one longitudinal side edge 12a to continually compensate for deviations in the path of travel of the one longitudinal side edge 12a of the thickened portion 12 and to insure that the traveling web 10 is longitudinally slit along the thinned portion 14 intermediate adjacent thickened portions 12 by cutting blade 51. In addition, it will be noted that the support member 38 is transversely shifted with the sensing head 42 for supporting the portion of the traveling web 10 engaged by the sensing head 42.

From the foregoing description it will be apparent that like operation will occur for self-aligning slitting apparatus 30 for longitudinally slitting the elongate web 10 along the other thinned portion 14 intermediate adjacent thickened portions 12.

it can be seen that this invention provides an apparatus for slitting a longitudinally traveling web having both longitudinally extending thickened and thinned portions in predetermined relation to a longitudinal side edge joining the thickened and thinned portions which is characterized by its ability to compensate for deviations in the path of travel of the one longitudinal side edge of the thickened portion.

In the drawings and specification there has been set forth a preferred embodiment of the invention and, although specific terms are employed, they are used in a generic and descriptive sense only and not for purposes of limitation.

What is claimed is:

1. An apparatus for slitting a longitudinally traveling elongate web having both longitudinally extending thickened and thinned portions joining each other at a longitudinal side edge of the thickened portion and being characterized by its ability to self-align to compensate for deviations in the path of travel of the one longitudinal side edge, said apparatus comprising a carriage mounted on one side of the traveling web for movement transversely of the traveling web, a sensing means comprising a sensing head carried by said carriage for transverse movement therewith for engaging a portion of either of said thickened and thinned portions, said sensing head being pivotally mounted on said carriage for movement under the influence of the traveling web substantially perpendicular to the traveling web out of engagement with one of said thickened and thinned portions into engagement with the other of said thickened and thinned portions,

severing means carried by said carriage for movement therewith and with said sensing means for longitudinally slitting the traveling web along a predetermined path,

double-acting reciprocating means operatively connected with said carriage and with said sensing means and said severing means for continuously shifting same in alternate opposite transverse directions, and

control means operatively associated with said reciprocating means and said sensing means and being responsive to said sensing means for actuating said reciprocating means in accordance with engagement of said sensing means with one of the thickened and thinned portions of the traveling web to transversely shift said sensing means and said severing means in a direction toward the other of the thickened and thinned portions to continually compensate for deviations in the path of travel of the one longitudinal side edge of the thickened portion, said control means comprising a pair of substantially identical current carrying coils carried by said carriage outwardly of said sensing means in longitudinally aligned end-to-end relation, and an elongate armature mounted longitudinally within said pair of current carrying coils and being operatively connected to said sensing means for movement longitudinally of said pair of current carrying coils in response to movement of said sensing means perpendicular to the traveling web for changing the respective impedence of each of said coils, and circuit means operatively associated with said reciprocating means and responsive to changes in the impedence of said coils for actuating said reciprocating means.

2. An apparatus, as set forth in claim 1, wherein said circuit means includes switch means having a first and second position, said switch means being in one of said positions when said sensing means is in engagement with the thickened portion for actuating said reciprocating means to transversely shift said sensing means and severing means toward the thinned portion and being in said other position when said sensing means is in engagement with the thinned portion for actuating said reciprocating means to transversely shift said sensing means and severing means toward the thickened portion.

3. An apparatus for slitting a longitudinally traveling elongate web having both longitudinally extending thickened and thinned portions joining each other at a longitudinal side edge of the thickened portion and being characterized by its ability to self-align to compensate for deviations in the path of travel of the one longitudinal side edge, said apparatus comprising a carriage mounted on one side of the traveling web for movement transversely of the traveling web,

a sensing head carried by said carriage for transverse movement therewith and disposed for movement, under the influence of the traveling web relative to said carriage, substantially perpendicular to the traveling web for alternative engagement with the thickened and thinned portions, support means disposed on the other side of the traveling web in opposed relation to said sensing head for supporting the portion of the traveling web in engagement with said sensing head and mounted for movement transversely of the traveling web, means connecting said support means with said carriage for transverse movement therewith so that said support means is maintained in supporting relation to said sensing head upon transverse movement thereof,

severing means carried by said carriage for movement with double-acting reciprocating means operatively connected with said carriage for continuously shifting same in alternative opposite, transverse directions, and

control means operatively associated with said reciprocating means and said sensing head and being responsive to said sensing head for actuating said reciprocating means in accordance with engagement of said sensing head with one of the thickened and thinned portions of the traveling web to transversely shift said sensing head and said severing means in a direction toward the other of the thickened and thinned portions to continually compensate for deviations in the path of travel of the one longitudinal side edge of the thickened portion, said control means comprising a pair of substantially identical current carrying coils carried by said carriage outwardly of said sensing head and longitudinally aligned in end-to-end relation, an elongate armature mounted longitudinally within said pair of current carrying coils and being operatively connected to said sensing head for movement longitudinally of said pair of current carrying coils in response to movement of said sensing head perpendicular to the traveling web for changing the respective impedence of each of said coils, and circuit means including switch means having a first and second position operatively associated with said reciprocating means and responsive to changes in the impedence of said coils for actuating said reciprocating means, said switch means being in one of said positions when said sensing head is in engagement with the thickened portion for actuating said reciprocating means to transversely shift said sensing head and severing means toward the thinned portion an being in said other position when said sensing head is in engagement with the thinned portion for actuating said reciprocating means to transversely shift said sensing head and severing means toward the thickened portion. 

1. An apparatus for slitting a longitudinally traveling elongate web having both longitudinally extending thickened and thinned portions joining each other at a longitudinal side edge of the thickened portion and being characterized by its ability to selfalign to compensate for deviations in the path of travel of the one longitudinal side edge, said apparatus comprising a carriage mounted on one side of the traveling web for movement transversely of the traveling web, a sensing means comprising a sensing head carried by said carriage for transverse movement therewith for engaging a portion of either of said thickened and thinned portions, said sensing head being pivotally mounted on said carriage for movement under the influence of the traveling web substantially perpendicular to the traveling web out of engagement with one of said thickened and thinned portions into engagement with the other of said thickened and thinned portions, severing means carried by said carriage for movement therewith and with said sensing means for longitudinally slitting the traveling web along a predetermined path, double-acting reciprocating means operatively connected with said carriage and with said sensing means and said severing means for continuously shifting same in alternate opposite transverse directions, and control means operatively associated with said reciprocating means and said sensing means and being responsive to said sensing means for actuating said reciprocating means in accordance with engagement of said sensing means with one of the thickened and thinned portions of the traveling web to transversely shift said sensing means and said severing means in a direction toward the other of the thickened and thinned portions to continually compensate for deviations in the path of travel of the one longitudinal side edge of the thickened portion, said control means comprising a pair of substantially identical current carrying coils carried by said carriage outwardly of said sensing means in longitudinally aligned endto-end relation, and an elongate armature mounted longitudinally within said pair of current carrying coils and being operatively connected to said sensing means for movement longitudinally of said pair of current carrying coils in response to movement of said sensing means perpendicular to the traveling web for changing the respective impedence of each of said coils, and circuit means operatively associated with said reciprocating means and responsive to changes in the impedence of said coils for actuating said reciprocating means.
 2. An apparatus, as set forth in claim 1, wherein said circuit means includes switch means having a first and second position, said switch means being in one of said positions when said sensing means is in engagement with the thickened portion for actuating said reciprocating means to transversely shift said sensing means and severing means toward the thinned portion and being in said other position when said sensing means is in engagement with the thinneD portion for actuating said reciprocating means to transversely shift said sensing means and severing means toward the thickened portion.
 3. An apparatus for slitting a longitudinally traveling elongate web having both longitudinally extending thickened and thinned portions joining each other at a longitudinal side edge of the thickened portion and being characterized by its ability to self-align to compensate for deviations in the path of travel of the one longitudinal side edge, said apparatus comprising a carriage mounted on one side of the traveling web for movement transversely of the traveling web, a sensing head carried by said carriage for transverse movement therewith and disposed for movement, under the influence of the traveling web relative to said carriage, substantially perpendicular to the traveling web for alternative engagement with the thickened and thinned portions, support means disposed on the other side of the traveling web in opposed relation to said sensing head for supporting the portion of the traveling web in engagement with said sensing head and mounted for movement transversely of the traveling web, means connecting said support means with said carriage for transverse movement therewith so that said support means is maintained in supporting relation to said sensing head upon transverse movement thereof, severing means carried by said carriage for movement with said sensing head and for longitudinally slitting the traveling web along the predetermined path, double-acting reciprocating means operatively connected with said carriage for continuously shifting same in alternative opposite, transverse directions, and control means operatively associated with said reciprocating means and said sensing head and being responsive to said sensing head for actuating said reciprocating means in accordance with engagement of said sensing head with one of the thickened and thinned portions of the traveling web to transversely shift said sensing head and said severing means in a direction toward the other of the thickened and thinned portions to continually compensate for deviations in the path of travel of the one longitudinal side edge of the thickened portion, said control means comprising a pair of substantially identical current carrying coils carried by said carriage outwardly of said sensing head and longitudinally aligned in end-to-end relation, an elongate armature mounted longitudinally within said pair of current carrying coils and being operatively connected to said sensing head for movement longitudinally of said pair of current carrying coils in response to movement of said sensing head perpendicular to the traveling web for changing the respective impedence of each of said coils, and circuit means including switch means having a first and second position operatively associated with said reciprocating means and responsive to changes in the impedence of said coils for actuating said reciprocating means, said switch means being in one of said positions when said sensing head is in engagement with the thickened portion for actuating said reciprocating means to transversely shift said sensing head and severing means toward the thinned portion and being in said other position when said sensing head is in engagement with the thinned portion for actuating said reciprocating means to transversely shift said sensing head and severing means toward the thickened portion. 